Vitamin D deficiency

and Martina Feichter, medical editor and biologist

Carola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.

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Martina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.

More about the experts All content is checked by medical journalists.

Vitamin D deficiency usually arises from the fact that the skin is not exposed to the sun too often. The body needs UV light for the body's own production of vitamin D3. However, a deficiency can also arise from illness. Read more on the topic: How does a vitamin D deficiency develop and manifest itself? What can be done against the undersupply?

Vitamin D Deficiency: Causes

Vitamin D deficiency (vitamin D3 deficiency) often occurs in people who spend most of their time indoors and rarely outdoors. The body covers most of its need for vitamin D through its own production with the help of sunlight. However, if the skin is not “supplied” with sufficient UV rays, the required vitamin D must increasingly be supplied through food or supplementary preparations.

However, it is difficult to meet the estimated daily vitamin D requirement through diet, even if you eat a balanced and varied diet. There are few foods that contain significant amounts of vitamin D.

Accordingly, a vitamin D deficiency is common in this country - the consequences of a lifestyle that takes place more indoors than outdoors and the low occurrence of vitamin D in food. In addition, illnesses are sometimes responsible for low vitamin D levels.

In summary, there is a risk of vitamin D deficiency, among other things:

• Insufficient exposure to the sun (especially for elderly people and residents as well as for people who hardly expose skin areas to the sun through clothing such as medals or chadors)
• Malnutrition or malnutrition
• impaired utilization and absorption of vitamin D (e.g. in chronic inflammatory bowel diseases, celiac disease, after major gastrointestinal operations)
• increased need (pregnancy and breastfeeding, children)
• Taking certain medications (e.g. anti-epilepsy drugs)
• increased excretion of vitamin D via the kidneys (renal insufficiency, nephrotic syndrome)

Vitamin D Deficiency: Symptoms

There are many symptoms of vitamin D deficiency, because the body needs vitamin D for a wide variety of processes. One of its main tasks is bone health. Vitamin D also supports the immune system, muscles and hair, for example.

Here are some of the possible effects of vitamin D deficiency:

• Hair loss
• increased susceptibility to infection
• Muscle weakness, muscle pain, body aches
• impaired bone mineralization (rickets in children, osteomalacia in adults) with bone pain and deformations
• neuromuscular hyperexcitability (tetany) due to calcium deficiency as a result of vitamin D deficiency with abnormal sensations (e.g. of the lips and fingers), muscle cramps, migraines, etc.

Vitamin D deficiency: depression, cancer & Co.

Apart from the above-mentioned vitamin D deficiency symptoms, there are also some serious illnesses that may be linked to a deficiency in vitamin D: depression, cancer, cardiovascular diseases (e.g. heart attack, stroke), respiratory diseases (such as asthma), metabolic diseases (such as Type 2 diabetes) and autoimmune diseases (such as multiple sclerosis) are among them. Several studies have found a connection between low vitamin D levels in the blood and diseases such as diabetes and rheumatism. Researchers suspect that winter depression could also be fueled by a vitamin D deficiency. In the case of many people, the blood level of the sun vitamin D rushes into the cellar in the dark, cold season - as does the mood.

For the most part, however, it is not clear whether the lack of vitamin D is the cause or a consequence of such diseases or whether an increased intake of vitamin D can help against the diseases mentioned. The connections that have been discovered need to be investigated in more detail.

According to the current state of knowledge, it is certain that a good supply of vitamin D can reduce the risk of falls, broken bones, loss of strength, loss of mobility and balance and premature death in older people.

Vitamin D Deficiency in Children

In children, the body is in constant change and growth. This makes it all the more important to have an adequate supply of nutrients and vitamins. Especially without sufficient vitamin D, the bones are unable to incorporate minerals from the blood into the bone substance. As a result, the bones remain soft and deform. Doctors then speak of rickets.

Infants have an increased risk of vitamin D deficiency and the resulting rickets - on the one hand because their breast milk contains very little vitamin D and on the other hand because the baby's delicate skin should not be exposed to direct sunlight. That is why the German Society for Pediatrics and Adolescent Medicine recommends that all babies from the end of the first week of life up to the end of the first year of life should receive a vitamin D tablet daily to prevent rickets. This recommendation applies to both breast-fed and non-breast-fed infants.

Vitamin D deficiency: test and diagnosis

If a vitamin D deficiency is suspected, a blood sample is taken to measure the serum concentration of 25-hydroxyvitamin-D (25-OH-vitamin-D). This is the storage form of vitamin D. It reflects the vitamin D supply through self-production and intake through food.

If the doctor suspects a disorder of the vitamin D metabolism or an increased calcium level, the blood level of the hormone calcitriol (1,25-vitamin D3) in the blood is measured. This is the biologically active form of vitamin D.

Test kits are now also available for use at home. With a vitamin D test like this, you usually poke your finger and send the blood sample to the laboratory indicated on the pack or on an enclosed information sheet. A few days later you will get the result.

Vitamin D Deficiency: Therapy

What to do if there is a vitamin D deficiency It can be compensated for in a number of ways, although it naturally plays a role in how it was created. Usually the cause is a lack of exposure to the sun. Then it can be enough to go outside regularly and expose your face, arms and hands to the sun uncovered and without sunscreen. How long this sun exposure should last for adequate vitamin D production depends, among other things, on the time of year and day, the geographical latitude and your own skin type. The skin should get enough sun, but not too much, so as not to increase the risk of skin cancer. According to the German Nutrition Society (DGE), the following recommendations for the duration of sunlight exposure apply to our latitudes in order to ensure good vitamin D production:

	Sunlight irradiation for skin type I / II *	Sunlight irradiation for skin type III **
March to May	10-20 minutes	15 to 25 minutes
June to August	5 - 10 minutes	10 to 15 minutes
September to October	10-20 minutes	15 to 25 minutes

* Skin type I / II: light to very light skin color, light red or blond hair, blue or green eyes

** Skin type III: medium skin tone, dark hair, brown eyes

Outside of midday (from 10 a.m. to 12 p.m. and from 3 p.m. to 6 p.m.), according to the DGE, you can stay in the sun twice as long as stated.

Vitamin D: Do lamps with UV radiation make sense?

Artificial UV radiation in solariums is not a suitable substitute for sunlight. It is not suitable for the treatment of vitamin D deficiency: it also contains UV-B rays - that part of the UV radiation that the body can use for vitamin D production and thus against vitamin D deficiency. However, solarium light also contains UV-A radiation, much more than sunlight. In addition to premature skin aging, this type of radiation primarily causes an increased risk of skin cancer.

Vitamin D in foods

The intake of vitamin D from food only covers a small part of our vitamin D requirements. Nevertheless, you should regularly consume foods that contain the sun vitamin. You can find out what these are in the article Vitamin D foods.

Vitamin D supplements

If a vitamin D deficiency cannot be compensated for through exposure to the sun and diet, vitamin D supplements can help. Talk to your doctor about whether such preparations make sense in your case and which dosage is advisable. This should be high enough to compensate for the vitamin D deficiency, but not too high so as not to risk overdosing in the long term.

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